1. Technical Field
The present disclosure relates to an antenna of a wireless terminal, and an antenna bushing thereof which improves antenna performance.
2. Description of the Related Art
In recent designs of wireless terminals such as smart phones, laptops and GPS devices, an extractable antenna has been employed to handle transmission/reception at relatively lower frequency bands, e.g., UHF and VHF, and in particular, to receive digital multimedia broadcasting (DMB) signals at those bands. This extractable antenna is typically separate and independent from other, built-in antennas used for communication at higher frequencies (e.g., cellular band frequencies). The extractable antenna is typically a monopole, whip type antenna extractable from the housing of the wireless terminal, and retractable back into the housing via manual manipulation. For the extractable antenna of a general purpose or the DMB, a reception type antenna has been broadly used, and the reception type antenna requires an antenna bushing to support the monopole radiator, the antenna bushing being part of an antenna module.
One of the factors that impede antenna performance is the electromagnetic interference (EMI) which is emitted from peripheral electronic components. The EMI disturbs and affects an electronic circuit coupled to the extractable antenna. The disturbance may interrupt or limit the effective performance of the antenna. It is also well known that the EMI causes signal loss along with lowering the antenna performance.
FIG. 1 is a diagram illustrating a related art antenna bushing of a wireless terminal 5, and its structure depicted in a side view. The antenna bushing 7 is fastened to a separate boss 8 by aligning a hole 2 of a fastening portion 3 with a hole of the boss 8 and utilizing a fastening member through the two holes. The boss 8 is different from a rear cover boss 6 used for assembling the rear cover together with a front cover.
The antenna bushing 7 is composed of an upper, closed collar portion 7a, a lower, partial collar portion 7b, the fastening portion 3 and a signal contact plate 4 which makes electrical contact at a signal contact point 4′ (shaded circle) with a receiver contact point (not shown) of the wireless terminal. An antenna signal beginning point 1 is considered approximately in a central region of the closed collar portion 7a, which is where good electrical contact between the antenna bushing 7 and the antenna radiator is made. The signal contact point 4′ is located at a vertical distance below the antenna signal beginning point 1. The longer this distance is, the higher the signal loss occurring due to the EMI. Particularly, when electronic components such as an ear jack, a motor, and sensors are installed adjacent to the antenna bushing, the amount of the signal loss increases due to the negative impact of the EMI emitted from such peripheral electronic components. Accordingly, there exists a need for an antenna bushing that improves the antenna performance while reducing the signal loss and enhancing the durability of the antenna.